The present invention relates to a fixed comb for a textile treatment or processing machine, specifically a combing machine, comprising a plurality of adjacent needles disposed in at least one row, which have, at least in sections, a working angle not equal to 90xc2x0 relative to the theoretical movement plane of the sliver being combed, wherein, viewed in the direction of the movement, a nipper unit is disposed before the fixed comb and a pair of take-off rollers is disposed after the fixed comb.
A fixed comb of the above type, or a combing machine with a fixed comb of the above type, is known, for example, from CH 679 590 A5. The known fixed comb has a free needle projection wherein the needles in that region are angled such that the angled region at the free end of the needle extends in the direction of the movement, viewed relative to the sliver. Solutions of this type are known also in various other embodiments, for example from EP 0 557 698 A1. Conventionally, the angling or curving of the needles is intended to achieve that the sliver becomes caught in the needles and is guided to their center region.
With this as the starting point, the invention has as its object to improve a fixed comb of the above type in such a way that an improvement of the combing result is attained at least in conjunction with certain types of textile treatment and processing machines.
This object is met according to the invention in such a way that the needles of the fixed comb in the region of the free needle projection have a working angle greater than 92xc2x0, particularly  greater than 95xc2x0. An optimal angle, for example, is 98xc2x0. Surprisingly it has been found that the result of such a design of the free needle projection is that the needle trim is always free, and the fibrous web is thus able to easily penetrate into the comb, and boll fragments, burl and noils accordingly are held back. Boll fragments, burls and noils that initially become stuck due to an unfavorable shape or size are pushed down into the comb-out position of the circular comb by the upper nipper element, off the fibers that remain in the comb and protrude out of the comb itself, after the combed staple has been taken off. By this process, which is aided by the inventive needle position, the fixed comb cleans itself during the combing process. In the subsequent combing cycle, the sliver end that was previously combed out by the circular comb can thus easily penetrate into the clean fixed comb. This results in less stress on the entire fixed comb as well as on its fastening components. Due to the lesser stress, which remains virtually constant during the entire operating time of the machine, the combing machine can be precisely adjusted, which results in an optimization of the combing process, i.e., specifically the percentage of long fibers in the combing waste is reduced and the combing process can be adapted to the desires of the individual customer. The inventive design can also be applied very advantageously in combination with a fixed comb that is known per se, which is additionally cleaned pneumatically.
In a further embodiment of the invention, provision may be made for the needles to be curved convexly against the direction of movement of the sliver. Specifically, the curvature of the needles and optionally that of the cover plates may be largely coaxial to the upper take-off roller. This results in the free needle projection extending very closely to the region between the two take-off rollers, which provides for an improvement in the combing result.
The invention will be explained in detail below, based on a preferred embodiment in conjunction with the drawing, in which: